In order to support progressively more complicated switching and path topologies, data center networks have become increasingly complex. For example, a Layer 2 multipath network (L2MP)—sometimes referred to as a fabric path switching System (FSS) or data center Ethernet—provides a non-blocking Layer 2 architecture that does not rely on the conventional spanning tree protocol to cut loops. That is, unlike a classical Ethernet, a L2MP may be configured to allow multiple paths between nodes at the data link layer (i.e., at the Ethernet layer). Instead, a link state protocol such as Intermediate System to Intermediate System (IS-IS) or Open Shortest Path First (OSPF) may be used to determine multiple, loop-free paths used to send packets to the same destination inside the L2 network.
A data center Ethernet may include a collection of gateway switches at the L2/L3 boundary used to forward frames towards (and receive frames from) destinations outside of the data center. Such gateways may be configured to provide redundancy using a First Hop Routing Protocol (FHRP), such as Hot Standby Router Protocol (HSRP) or Virtual Router Redundancy Protocol (VRRP), and static load balancing may be achieved among the gateways using multiple-group FHRP. However, a large data center network may include 16 or even 32 such gateways. Using the current implementation of HSRP or VRRP does not scale or provide for dynamic load balancing at the L2/L3 boundary as gateways are added (or removed) from an FHRP group. This occurs because the number of paths that must be configured on each access switch grows geometrically with each additional gateway and FHRP group. In such cases, reconfiguring hundreds of routing entries each time a gateway is added (or removed) to a L2MP network is simply impractical.